Sirdavidia, an Extroardinary New Genus of Annonaceae from Gabon
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A peer-reviewed open-access journal PhytoKeys 46: 1–19 (2015)Sirdavidia, an extraordinary new genus of Annonaceae from Gabon 1 doi: 10.3897/phytokeys.46.8937 RESEARCH ARTICLE http://phytokeys.pensoft.net Launched to accelerate biodiversity research Sirdavidia, an extraordinary new genus of Annonaceae from Gabon Thomas L.P. Couvreur1,2,3, Raoul Niangadouma4, Bonaventure Sonké2,5,6, Hervé Sauquet7 1 Institut de Recherche pour le Développement, UMR-DIADE, BP 64501, F-34394 Montpellier cedex 5, France. 2 University of Yaoundé I, Higher Teacher’s Training College, Plant Systematic and Ecology Laborato- ry, P.O. Box 047, Yaoundé, Cameroon 3 Naturalis Biodiversity Centre, Botany Section, Darwinweg 2, 2333 CR Leiden, The Netherlands 4 National Herbarium of Gabon, R.D. 1135, Libreville, Gabon 5 Missouri Botanical Garden, Africa & Madagascar Department, P.O. Box 299, St. Louis, Missouri 63166-0299, USA 6 Université Libre de Bruxelles, Herbarium et Bibliothèque de Botanique africaine, CP 169, Av. F. Roosevelt 50, B-1050, Brussels, Belgium 7 Université Paris-Sud, Laboratoire Écologie, Systématique, Évolution, CNRS UMR 8079, 91405 Orsay, France Corresponding author: Thomas L.P. Couvreur ([email protected]) Academic editor: Pavel Stoev | Received 12 November 2014 | Accepted 19 January 2015 | Published 4 February 2015 Citation: Couvreur TLP, Niangadouma R, Sonké B, Sauquet H (2015) Sirdavidia, an extraordinary new genus of Annonaceae from Gabon. PhytoKeys 46: 1–19. doi: 10.3897/phytokeys.46.8937 Abstract A distinctive new monotypic genus from Gabon is described in the tropical plant family Annonaceae: Sirdavidia, in honor to Sir David Attenborough. Molecular phylogenetic analyses confirm thatSirdavidia , which is very distinct from a morphological standpoint, is not nested in any existing genus of Annonaceae and belongs to tribe Piptostigmateae (subfamily Malmeoideae), which now contains a total of six genera. The genus is characterized by long acuminate leaves, fully reflexed red petals, 16–19 bright yellow, loosely arranged stamens forming a cone, and a single carpel topped by a conspicuous stigma. With just three known collections, a preliminary IUCN conservation status assessment is provided as “endangered” as well as a distribution map. The discovery of Sirdavidia is remarkable at several levels. First, it was collected near the road in one of the botanically best-known regions of Gabon: Monts de Cristal National Park. Second, its sister group is the genus Mwasumbia, also monotypic, endemic to a small area in a forest in Tanzania, some 3000 km away. Finally, the floral morphology is highly suggestive of a buzz pollination syndrome. If confirmed, this would be the first documentation of such a pollination syndrome in Mag- noliidae and early-diverging angiosperms in general. Copyright Thomas L.P. Couvreur et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. 2 Thomas L.P. Couvreur et al. / PhytoKeys 46: 1–19 (2015) Résumé Un nouveau genre monotypique du Gabon est décrit dans la famille tropicale des Annonaceae : Sirda- vidia, en honneur à Sir David Attenborough. Des analyses phylogénétiques confirment que Sirdavidia, caractérisé par une morphologie unique, n’appartient à aucun genre connu d’Annonaceae et se place au sein de la tribu des Piptostigmateae (dans la sous-famille des Malmeoideae), laquelle compte désormais un total de six genres. Le genre est caractérisé par des feuilles avec un long acumen, des pétales rouges réfléchis, 16–19 étamines jaunes qui forment un cône lâche et un carpelle surmonté d’un stigmate bien visible. Avec seulement trois récoltes connues, un statut de conservation préliminaire de “endangered” est proposé sur la base des critères de l’UICN. Une carte de distribution est également fournie. La découverte de Sirdavidia est remarquable pour plusieurs raisons. Tout d’abord le nouveau genre a été collecté près de la route dans l’une des régions les plus connues botaniquement du Gabon : le Parc National des Monts de Cristal. Ensuite, son groupe-frère est le genre, Mwasumbia, également monotypique, endémique d’une petite région en Tanzanie à plus de 3000 km. Enfin, les caractères floraux suggèrent un syndrome de pol- linisation appélé « buzz pollination». Si cela se confirme, ce sera la première documentation de ce type de syndrome pour les Magnoliidae et les Angiospermes basales en général. Keywords Piptostigmateae, Monts de Cristal, buzz pollination, vicariance, Annonaceae, Central Africa, Magnoliidae Introduction The Central African country of Gabon is merely 270 000 km² in size, but is home to an incredible botanical diversity (Sosef et al. 2006). Around 82% of its territory is covered with tropical rain forest and with around 5000 vascular plant species, Gabon is an important center of plant biodiversity in Central Africa (Sosef et al. 2006). The country is botanically one of the best known in the region (Sosef et al. 2006; Wieringa and Sosef 2011) with several parts of its territory well inventoried, such as the Monts de Cristal area (Wieringa and Sosef 2011). Annonaceae (Magnoliidae) is a pantropical flowering plant family of trees, shrubs and lianas. With around 2500 species (Chatrou et al. 2012; Couvreur et al. 2011) it is one of the most diverse plant families in tropical rain forests, and the largest in order Magnoliales (Haywood et al. 2009). Recently a new phylogenetic classification of the family recognizes four subfamilies and 14 tribes (Chatrou et al. 2012). This was fol- lowed by a scratchpad website (World Annonaceae; Couvreur 2014b) documenting Annonaceae diversity and taxonomy worldwide. Taxonomic understanding of African Annonaceae has been increasing since the publication of “Flore du Gabon, Annon- aceae, volume 16” (Le Thomas 1969) more than 40 years ago (Botermans et al. 2011; Couvreur 2009; Couvreur 2014a; Deroin and Luke 2005; Fero et al. 2014; Versteegh and Sosef 2007). As a consequence, several new species and a new genus have been described in Africa these past years, mainly from Tanzania (Couvreur et al. 2006; Couvreur et al. 2009; Johnson et al. 1999; Luke and Deroin 2005; Marshall et al. in press). New species, however, from Central Africa, and in particular Gabon, have been rarer with only a few such descriptions (Jongkind 2002). Sirdavidia, an extraordinary new genus of Annonaceae from Gabon 3 A probable new genus of Annonaceae was collected during field work in Monts de Cristal National Park, as part of a larger field trip focusing on the study Magnoliidae floral diversity. The objective of this paper was to confirm its status as a new species and its classification in a new genus. The taxon was first seen near the Kinguélé dam, and further prospection in the area revealed several individuals. It is the unusual floral structure of this species for Annonaceae that led us to suspect it might represent a new taxon and to undertake both a phylogenetic analysis and more thorough morphologi- cal observations. As we show here, interesting tropical taxa unknown to science can still be discovered in places even considered to be well known botanically. Material and methods Herbarium, alcohol and photographic materials were used to produce the descriptions. In order to identify other specimens of this new genus, we looked at all undetermined Annonaceae specimens in the herbaria located at BR, BRLU, LBV, P and YA (her- barium acronyms according to Thiers 2012). We also looked at sterile plot specimens of Annonaceae for Gabon held at BRLU. The conservation status was assessed by calculating the extent of occurrence (EOO) and the area of occupancy (AOO) using the GeoCAT tool (Bachman et al. 2011) and applying the IUCN Red List Category criteria (Standards-and-Petitions-Working-Group 2006). A preliminary phylogenetic analysis indicated that the new taxon was nested in tribe Piptostigmateae of the Malmeoideae subfamily. Therefore, the data matrix of Couvreur et al. (2009) was used to undertake the analyses. The matrix was based on two plastid markers (rbcL and trnL intron / trnL-trnF spacer) and contains 35 out of the 47 genera of Malmeoideae, representing all major lineages. Representative species from all other subfamilies were also sampled: Anaxagoreoideae (1 genus), Ambavioide- ae (2 genera out of 8), Annonoideae (17 genera out of 50). Eupomatia bennettii (Eu- pomatiaceae) was chosen as the outgroup (Massoni et al. 2014; Sauquet et al. 2003). All six genera currently recognized in Piptostigmateae were sampled. Sampling within genera was restricted to one species in the Annonoideae and Ambavioideae, and varied from one to two species in the Malmeoideae. DNA extractions of silicagel-dried leaf samples from two individuals of Sirdavidia solannona Couvreur & Sauquet were performed using a DNeasy Plant Mini Kit (Qiagen, Valencia, CA). The universal primers C/D and E/F (Taberlet et al. 1991) were used to amplify and sequence the trnL intron and trnL-trnF spacer. The rbcL marker was amplified using two primer combinations, 1F/724R and 636F/1460R (Fay et al. 1998). PCR amplifications were conducted using the FailSafe kit with Premix E (Epicentre, Madison, WI), according to manufacturer’s instructions and by adding 0.5 U of Taq DNA polymerase (Promega, Madison, WI) in a total volume of 50 μL. The PCR program was as follows: 35 thermal cycles at 94 °C for 1 min, 50–55 °C for 50 s, 72 °C for 50 s and a final extension at 72 °C for 3 min. Sequencing was performed at Macrogen (The Netherlands). Sequences were edited using Geneious 1.5.6 4 Thomas L.P. Couvreur et al. / PhytoKeys 46: 1–19 (2015) (Drummond et al. 2010) and manually aligned in the PAUP* text editor (version 4.10b; Swofford 2002). Gaps were coded following the simple coding model of Simmons and Ochoterena (2000). Microsatellites and ambiguously aligned regions (in the trnL intron and trnL-trnF spacer) were excluded from the analyses.